openvpn: Allow override of interface name

If using a configuration file for OpenVPN, allow overriding name of the
interface. The reason is that then people could use configuration file
provided by VPN provider directly and override the name of the interface
to include it in correct firewall zone without need to alter the
configuration file.

Signed-off-by: Michal Hrusecky <michal@hrusecky.net>
(cherry picked from commit c93667358515ec078ef4ac96393623ac084e5c9e)

package/network/services/openvpn/Makefile

@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 PKG_NAME:=openvpn
 
 PKG_VERSION:=2.4.9
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE_URL:=\
 	https://build.openvpn.net/downloads/releases/ \

package/network/services/openvpn/files/openvpn.init

@@ -69,6 +69,40 @@ section_enabled() {
 	[ $enable -gt 0 ] || [ $enabled -gt 0 ]
 }
 
+openvpn_get_dev() {
+	local dev dev_type
+	local name="$1"
+	local conf="$2"
+
+	# Do override only for configurations with config_file
+	config_get config_file "$name" config
+	[ -n "$config_file" ] || return
+
+	# Check there is someething to override
+	config_get dev "$name" dev
+	config_get dev_type "$name" dev_type
+	[ -n "$dev" ] || return
+
+	# If there is a no dev_type, try to guess it
+	if [ -z "$dev_type" ]; then
+		. /lib/functions/openvpn.sh
+
+		local odev odev_type
+		get_openvpn_option "$conf" odev dev
+		get_openvpn_option "$conf" odev_type dev-type
+		[ -n "$odev_type" ] || odev_type="$odev"
+
+		case "$odev_type" in
+			tun*) dev_type="tun" ;;
+			tap*) dev_type="tap" ;;
+			*) return;;
+		esac
+	fi
+
+	# Return overrides
+	echo "--dev-type $dev_type --dev $dev"
+}
+
 openvpn_add_instance() {
 	local name="$1"
 	local dir="$2"
@@ -83,7 +117,8 @@ openvpn_add_instance() {
 		--config "$conf" \
 		--up "/usr/libexec/openvpn-hotplug up $name" \
 		--down "/usr/libexec/openvpn-hotplug down $name" \
-		--script-security "${security:-2}"
+		--script-security "${security:-2}" \
+		$(openvpn_get_dev "$name" "$conf")
 	procd_set_param file "$dir/$conf"
 	procd_set_param term_timeout 15
 	procd_set_param respawn